The present invention relates to a method for controlling an upshift process in a dual-clutch gearbox having a dual-clutch gearbox input shaft connected to a drive engine, having two friction clutches and having two partial gearboxes.
Dual-clutch gearboxes of said type are generally known. Even-numbered gear stages are assigned to one of the two partial gearboxes while odd-numbered gear stages are assigned to the other partial gearbox. By means of overlapping actuation of the friction clutches assigned to the partial gearboxes, it is possible to carry out gearshifts from one gear to the next without an interruption in tractive force.
Numerous methods have become known for carrying out shift processes in dual-clutch gearboxes.
For example, DE 103 49 220 A1 describes a method of said type in which comfort is improved by virtue of the control of the shift process in the gearbox from the source gear to the target gear and the control of the associated friction clutch taking place such that the engine rotational speed runs in the direction of the synchronizing rotational speed of the target gear with a virtually constant gradient.
Document DE 10 2006 010 934 A1 proposes the damping of vibrations in the active and/or inactive partial gearbox by engaging the associated clutch before the synchronization in the active partial gearbox, and subsequently carrying out a synchronization.
The method is designed to prevent so-called synchronizing shocks during downshift processes (for example from the fourth into the second gear).
Document DE 10 2006 002 490 deals with a similar problem and discloses a method for carrying out a double traction downshift, with a gear temporarily being engaged whose gradation lies between that of the source gear and that of the target gear.
Here, the intention is to make it possible, during the engagement of the intermediate gear, for a torque shock to be transmitted into the free partial gearbox via the friction clutch which is assigned to said partial gearbox, in order to thereby accelerate approximately to the target rotational speed in a similar manner to double-declutching, as was required during downshifting in manual gearboxes before the introduction of synchronizers.